Sociodemographic and anthropometric characteristics of the study population
We included 80 children among whom 49 (61.2%) boys divided into 21 (26.2%) LBW, 45 (56.2%) NBW and 14 (15.5%) HBW. The median (IQR) age was 7.3 (6.3-8.1) years with no significant difference according to BW groups (p=0.32). The median (IQR) for weight, height and BMI were respectively 23.3 (21.0-27.8) kg, 124 (116-134) cm and 15.3 (14.6-16.8) kg/m2 with no significant difference with respect to BW strata (all p>0.211). There were 17 (21.2%) overweight/obese children without any difference with BW groups (p=0.665), Table 1.
Table 1: Sociodemographic and anthropometric characteristics of the study population
Variables
|
Total
|
LBW
|
NBW
|
HBW
|
p-value
|
N (%)
|
80 (100)
|
21 (26.2)
|
45 (56.2)
|
14 (17.5)
|
-
|
Median age, years (IQR)
|
7.3 (6.3-8.1)
|
6.9 (6.2-7.9)
|
7.1 (6.5-8.2)
|
7.2 (6.3-8.1)
|
0.7
|
Gender, boys (%)
|
49 (61.2)
|
12 (57.1)
|
26 (57.8)
|
11 (78.6)
|
0.32
|
Median weight, kg (IQR)
|
23.3 (21-27.8)
|
23 (20-25.3)
|
23 (21.5-26.7)
|
27.5 (20.6-32.8)
|
0.215
|
Median weight, percentile (IQR)
|
50 (15-82)
|
25 (15-62.5)
|
50 (15-80)
|
62.5 (24-90)
|
0.381
|
Weight Percentile groups (%)
|
|
|
|
|
|
<5th
|
3 (3.8)
|
0 (0)
|
1 (2.2)
|
2 (14.3)
|
|
5-94th
|
64 (80)
|
18 (85.7)
|
36 (80)
|
10 (71.4)
|
0.233
|
≥95th
|
13(16.2)
|
3 (14.3)
|
8 (17.8)
|
2 (14.3)
|
|
Median height, cm (IQR)
|
124 (116-134)
|
123 (114-135)
|
122 (119-130)
|
128 (115-136)
|
0.577
|
Median height, percentile (IQR)
|
50.0 (25-82.5)
|
50 (20-75)
|
50 (20-85)
|
50 (25-78.8)
|
0.833
|
Height percentile groups (%)
|
|
|
|
|
|
<5th
|
2 (2.5)
|
1 (2.5)
|
1 (2.2)
|
0 (0)
|
|
5-94th
|
70 (87.5)
|
18 (85.7)
|
39 (86.7)
|
13 (92,9)
|
0.862
|
≥95th
|
8 (10)
|
2 (9.5)
|
5 (11.1)
|
1 (7.1)
|
|
Median BMI, kg/m2 (IQR)
|
15.3 (14.6-16.8)
|
14.7 (14.1-16.8)
|
15.3 (14.8-17.1)
|
16.0 (14.8-17.5)
|
0.211
|
Median BMI, percentile (IQR)
|
50 (25-75)
|
25 (10-75)
|
50 (25-75)
|
50 (22.5-86.3)
|
0.342
|
BMI Percentile groups (%)
|
|
|
|
|
|
<5th
|
5 (6.2)
|
1 (4.8)
|
2 (4.4)
|
2 (14.3)
|
|
5-84th
|
58 (72.5)
|
16 (76.2)
|
34 (75.6)
|
8 (57.1)
|
0.665
|
≥85th
|
17 (21.2)
|
4 (19)
|
9 (20)
|
4 (28.6)
|
|
BMI – Body mass index; HBW – High birth weight; IQR – Interquartile range; LBW – Low birth weight; NBW – Normal birth weight
Maternal and birth history of participants
As presented in Table 2, the median (IQR) maternal age was 28 (23.2-32.0) years with no significant difference in BW (p=0.486). Amongst the 10 (12.5%) of multiple pregnancies, 9 (90%) led to LBW infants with a statistical significance (p<0.001). We observed that 3 (3.7%) women had diabetes mellitus among whom 2 (66.7%) delivered HBW children with a statistical significance (p=0.048). In Table 3, the median (IQR) BW was 3200 (2421.5-3678.8) g with 2150 (1885-2375) g for LBW, 3200 (2900-3500) g for NBW and 4350 (4165-4642) g for HBW children (p<0.001). The median (IQR) gestational age was 39 (38-40) weeks, with 10 (47.6%) LBW children born before 37 weeks (p<0.001). All LBW children born before 37 weeks had a BW small for gestational age.
Table 2: Maternal history during pregnancy
Variables
|
Total
|
LBW
|
NBW
|
HBW
|
p-value
|
N (%)
|
80 (100)
|
21 (26.2)
|
45 (56.2)
|
14 (17.5)
|
-
|
Median Maternal Age, years (IQR)
|
28 (23.2-32)
|
29 (24.5-33)
|
27 (23- 31.5)
|
30 (24- 34)
|
0.486
|
Type of Pregnancy (%)
|
|
|
|
|
|
Single
|
70 (87.5)
|
12 (57.1)
|
44 (97.8)
|
14 (100)
|
|
Multiple
|
10 (12.5)
|
9 (42.9)
|
1 (2.2)
|
0 (0)
|
<0.001
|
Maternal Illness (%)
|
|
|
|
|
|
Hypertension
|
4 (5.0)
|
2 (9.5)
|
2 (4.4)
|
0 (0)
|
0.335
|
Diabetes
|
3 (3.7)
|
1 (4.8)
|
0 (0)
|
2 (14.3)
|
0.048
|
HIV infection
|
3 (3.7)
|
1 (4.8)
|
1 (2.2)
|
1 (7.1)
|
0.687
|
Hepatitis B infection
|
1 (1.2)
|
0 (0)
|
1 (2.2)
|
0 (0)
|
0.09
|
Smoking (%)
|
1 (1.2)
|
0 (0)
|
1 (2.2)
|
0 (0)
|
0.5
|
Alcohol consumption (%)
|
12 (15)
|
3 (14.3)
|
8 (17.8)
|
1 (7.1)
|
0.582
|
HBW – High birth weight; IQR – Interquartile range; LBW – Low birth weight; NBW – Normal birth weight
Table 3: Birth Characteristics
Variables
|
Total
|
LBW
|
NBW
|
HBW
|
p-value
|
N (%)
|
80 (100.0)
|
21 (26.2)
|
45 (56.2)
|
14 (17.5)
|
-
|
Median birth weight, grams (IQR)
|
3200 (2421.5-3678.8)
|
2150(1885-2375)
|
3200 (2900-3500)
|
4350(4165-4642)
|
<0.001
|
Median gestational age, weeks (IQR)
|
39 (38-40)
|
37 (34-38)
|
39 (38-40)
|
39.5 (38-40)
|
<0.001
|
Gestational age groups, weeks (%)
|
|
|
|
|
|
<37
|
13 (16.2)
|
10 (47.6)
|
1 (2.2)
|
02 (14.3)
|
|
37-42
|
67 (83.8)
|
11 (56.4)
|
44 (97.8)
|
12 (85.7)
|
<0.001
|
>42
|
0 (0)
|
0 (0)
|
0 (0)
|
0 (0)
|
|
Child reanimated at birth
|
21 (26.2)
|
10 (47.6)
|
08 (17.8)
|
03 (21.4)
|
0.098
|
Child hospitalised at birth
|
24 (30)
|
9 (42.9)
|
10 (22.2)
|
5 (35.7)
|
0.209
|
HBW – High birth weight; IQR – Interquartile range; LBW – Low birth weight; NBW – Normal birth weight
Blood pressure characteristics
The median (IQR) SBP and DBP was respectively 91 (85.3-97.8) mmHg and 56 (52.0-58.8) mmHg, without any statistical significance according to BW groups (all p>0.187). There were 2 (2.5%) children with an elevated BP; both had a NBW, giving a prevalence of 4.4% of NBW children with an elevated blood pressure. Hypertension was observed in 2 (2.5%) children who all had a LBW, giving a prevalence of 9.5% among LBW population (see Table 4). None of the HBW children had an elevated BP or hypertension. Hypertension and elevated BP were not significantly associated with BW (p=0.233).
Table 4: Blood pressure characteristics
Variables
|
Total
|
LBW
|
NBW
|
HBW
|
p-value
|
N (%)
|
80 (100)
|
21 (26.2)
|
45 (56.2)
|
14 (17.5)
|
-
|
Median SBP, mmHg (IQR)
|
91 (85.3-97.8)
|
94 (85.5-100.5)
|
90 (85-95)
|
92 (89.3-101)
|
0.187
|
Median SBP, percentile (IQR)
|
49 (49-50)
|
49 (49-51)
|
49 (49-49.5)
|
49 (49-51)
|
0.118
|
Median DBP, mmHg (IQR)
|
56 (52-58.8)
|
57 (53-60)
|
55 (51-57)
|
57 (50-60.3)
|
0.242
|
Median DBP, percentile (IQR)
|
49 (49-50.1)
|
50 (49-51)
|
49 (49-50)
|
49.5 (49-50)
|
0.219
|
SBP Percentile
|
|
|
|
|
|
<90
|
78 (97.5)
|
19 (90.5)
|
45 (100)
|
14 (100)
|
|
90-94
|
1 (1.2)
|
1 (4.8)
|
0 (0)
|
0 (0)
|
0.24
|
≥95
|
1 (1.2)
|
1 (4.8)
|
0 (0)
|
0 (0)
|
|
DBP Percentile
|
|
|
|
|
|
<90
|
77 (96.2)
|
19 (97.5)
|
44 (97.8)
|
14 (100)
|
|
90-94
|
2 (2.5)
|
1 (4.8)
|
1 (2.2)
|
0 ()
|
0.429
|
≥95
|
1 (1.2)
|
1 (4.8)
|
0 (0)
|
0 (0)
|
|
BP Percentile
|
|
|
|
|
|
<90
|
76 (95)
|
19 (90.5)
|
43 (95.6)
|
14 (100)
|
|
90-94
|
2 (2.5)
|
0 (0)
|
2 (4.4)
|
0 (0)
|
0.233
|
≥95
|
2 (2.5)
|
2 (9.5)
|
0 (0)
|
0 (0)
|
|
DBP – Diastolic blood pressure; HBW – High birth weight; IQR - Interquartile range; LBW – Low birth weight; NBW – Normal birth weight; SBP – Systolic blood pressure
Proteinuria and glomerular filtration rate characteristics
In Table 5, dipstick positive proteinuria was observed in 15 (18.8%) children, with a significantly higher prevalence in LBW (28.6%) and HBW (35.7%) children compared with NBW (8.1%) ones (p=0.033). For the 15 children who performed PCR, the median (IQR) PCR was 185 (130-373) mg/g without any significant difference according to BW classes (p=0.228). A proteinuria was noticed in 7 (8.7%) children with a higher prevalence in LBW (19%) and HBW (14.3%) in comparison to NBW (2.2%) children, at the limit of statistical significance (p=0.051). The median (IQR) eGFR was 105.5 (90-118) ml/min/1.73m2 without any significant difference with regards to BW groups (p=0.330). There was a decreased eGFR in 18 (22.5%) children with an increased prevalence according to BW groups, ranging from 3 (14.3%) LBW, 11 (24.4%) NBW to 4 (28.6%) HBW children (p=0.818).
Table 5: Proteinuria and glomerular filtration rate characteristics
Variables
|
Total
|
LBW
|
NBW
|
HBW
|
p-value
|
N (%)
|
80 (100)
|
21 (26.2)
|
45 (56.2)
|
14 (17.5)
|
-
|
Dipstick positive proteinuria, n (%)
|
15 (18.8)
|
6 (28.6)
|
4 (8.1)
|
5 (35.7)
|
0.033
|
Median PCR, mg/g (IQR), (n=15)
|
185 (130-373)
|
291 (162-455)
|
143 (96.5-215)
|
185 (85-215)
|
0.228
|
Median SCr, mg/dl (IQR) (n=80)
|
0.64 (0.59-0.73)
|
0.62 (0.56-0.68)
|
0.66 (0.6-0.72)
|
0.63 (0.53-0.82)
|
0.339
|
Median eGFR, ml/min/1.73m2 (IQR), (n=80)
|
105.5 (90-118)
|
113 (95-124)
|
103 (89-114.5)
|
109 (87.2-122)
|
0.33
|
PCR ratio mg/g (%), (n=15)
|
|
|
|
|
|
<200
|
73(91.2)
|
17(81)
|
44 (97.8)
|
12 (85.7)
|
0.051
|
≥200
|
7(8.7)
|
4(19)
|
1 (2.2)
|
2 (14.3)
|
|
eGFR ml/min (%), (n=80)
|
|
|
|
|
|
≥120
|
18 (22.5)
|
6 (28.6)
|
9 (20)
|
3 (21.4)
|
|
90-119
|
44 (55)
|
12 (57.1)
|
25 (55.6)
|
7 (50)
|
0.818
|
<90
|
18 (22.5)
|
3 (14.3)
|
11(24.4)
|
4 (28.6)
|
|
eGFR – Estimated glomerular filtration rate ; HBW – High birth weight; IQR - Interquartile range; LBW – Low birth weight; NBW – Normal birth weight; PCR – Protein to creatinine ratio ; SCr – Serum creatinine
Effect of prematurity, weight for gestational age and overweight/obesity on blood pressure, proteinuria and glomerular filtration rate
As presented in Table 6, gestational age did not significantly affect any of these parameters. When comparing with NBW, LBW had significantly higher SBP (p=0.029); however, LBW and HBW children had a trend toward an increase DBP, PCR and eGFR with no statistical significance. We observed that overweight/obese children had significantly high SBP and DBP, and a reduced eGFR (all p<0.037).
Table 6: Effect of prematurity, weight for gestational age and obesity on BP, proteinuria and eGFR
variables
|
Gestational age
|
|
Weight for gestational age
|
|
Overweight/obesity
|
|
< 37 weeks
|
37-42 weeks
|
p
|
|
LBW
|
NBW
|
p
|
NBW
|
HBW
|
p
|
|
Yes
|
No
|
p
|
SBP, mmHg
|
94.0 (90.5-100.5)
|
90.0 (85.0-97.0)
|
0.101
|
|
94.0 (85.5-100.5)
|
90.0 (85.0-95.0)
|
0.138
|
90.0 (85.0-95.0)
|
92.0 (89.3-101.0)
|
0.116
|
|
97.0 (88.5-106.0)
|
90.0 (85.0-95.0)
|
0.011
|
SBP, percentile
|
49.0 (49.0-51.0)
|
49.0 (49.0-50.0)
|
0.264
|
|
49.0 (49.0-51.0)
|
49.0 (49.0-49.5)
|
0.029
|
49.0 (49.0-49.5)
|
49.0 (49.0-51.0)
|
0.375
|
|
50.0 (49.0-51.0)
|
49.0 (49.0-50.3)
|
0.018
|
DBP, mmHg
|
57.0 (51.5-60.5)
|
56.0 (52.0-58.0)
|
0.472
|
|
57.0 (53.0-60.0)
|
55.0 (51.5-57.5)
|
0.078
|
55.0 (51.5-57.5)
|
57.0 (50.0-60.3)
|
0.343
|
|
58.0 (55.0-64.5)
|
55.0 (52.0-58.0)
|
0.037
|
DBP,percentil
|
50.0 (49.0-51.0)
|
49.0 (49.0-50.0)
|
0.066
|
|
50.0 (49.0-51.0)
|
49.0 (49.0-50.0)
|
0.060
|
49.0 (49.0-50.0)
|
49.5 (49.0-50.0)
|
0.736
|
|
50.0 (49.0-51.0)
|
49.0 (49.0-50.0)
|
0.146
|
PCR, mg/g
|
150 (100-190)
|
200 (100-200)
|
0.922
|
|
200 (100-200)
|
100 (100-180)
|
0.221
|
100 (100-180)
|
200 (100-200)
|
0.322
|
|
100 (100-200)
|
200 (100-200)
|
0.480
|
SCr, mg/dl
|
0.64 (0.60-0.74)
|
0.64 (0.58-0.73)
|
0.695
|
|
0.63 (0.56-0.68)
|
0.66 (0.61-0.76)
|
0.119
|
0.66 (0.61-0.76)
|
0.64 (0.53-0.83)
|
0.605
|
|
0.69 (0.62-0.84)
|
0.63 (0.58-0.73)
|
0.058
|
eGFR, ml/min
|
99.0 (91.0-117.5)
|
106.0 (90.0-118.0)
|
0.506
|
|
113.0 (95.0-124.0)
|
103.0 (89.5-114.5)
|
0.187
|
103.0 (89.5-114.5)
|
109.5 (87.3-122.0)
|
0.449
|
|
93.0 (81.5-109.5)
|
106.0 (93.0-121.0)
|
0.036
|
Estimates are median and interquartile range. DBP – Diastolic blood pressure; eGFR – Estimated glomerular filtration rate ; HBW – High birth weight; LBW – Low birth weight; NBW – Normal birth weight; PCR – Protein to creatinine ratio ; SBP – Systolic blood pressure; SCr – Serum creatinine
Correlations between birth weight and variables
There was an inverse relationship between BW and SBP, DBP, PCR and eGFR although with no significant difference (all p>0.05). However, we observed a significant weak positive correlation between BW and weight (r=0.231) as well as BMI (r=0.269), and a negative correlation between BW and weight percentile (r=-0.241) (all p<0.039) (Table 7).
Table 7: Correlation between birth weight and others variables
Variables
|
Coefficient
|
p-value
|
Age
|
0.006
|
0.955
|
Maternal age
|
0.096
|
0.397
|
Weight
|
0.231
|
0.039
|
Weight percentile
|
-0.241
|
0.031
|
Height
|
0.108
|
0.343
|
Height percentile
|
0.147
|
0.193
|
BMI
|
0.269
|
0.016
|
BMI percentile
|
0.240
|
0.032
|
SBP
|
-0.014
|
0.904
|
SBP percentile
|
-0.116
|
0.306
|
DBP
|
-0.004
|
0.975
|
DBP percentile
|
-0.078
|
0.493
|
BP percentile
|
-0.140
|
0.215
|
PCR
|
-0.181
|
0.520
|
Serum creatinine
|
0.106
|
0.350
|
eGFR
|
-0.073
|
0.518
|
BMI – Body mass index; BP – Blood pressure; DBP – Diastolic blood pressure; eGFR – Estimated glomerular filtration rate; PCR – Protein to creatinine ratio ; SBP – Systolic blood pressure